1. Field of the Invention
The present invention relates to a rotary blade used in a tile cutter and more particularly to a rotary blade assembly that includes a rotary blade for cutting ceramic tiles that will be installed on the surfaces of walls, floors, etc.
2. Prior Art
A conventional device for cutting tiles to prescribed dimensions includes a base plate, guide rails installed above the base plate, an operating lever provided on the guide rails so as to pivot and slide above the base plate, a rotary blade mounted to the operating lever so as to cut a tile placed on the base plate, and a pressing plate affixed to the operating lever so as to press and split the tile.
FIG. 2 shows a tile cutter of this type.
In this Figure, the reference numeral 1 is a roughly rectangular base plate. The base plate 1 has a central projecting strip 2 oriented in the direction of the length of the base plate 1. Tile supporting surfaces 3 are formed roughly at the same height as the projecting strip 2 on both sides of the projecting strip 2. The tile supporting surfaces 3 are covered with elastic films.
A pair of guide rails 4 are supported by stands 5 which are installed at both ends of the base plate 1. The guide rails 4 are positioned above the projecting strip 2, and a lever slider 6 is installed on the guide rails 4. The lever slider 6 is free to move or slide on the guide rails 4. A pivotal operating lever 7 that has a base part 8 is connected to the lever slider 6, andrea rotary blade 9 is attached to the lower end of this base part 8. In addition, a pressing plate 10 is installed on the lower end of the base part 8 of the operating lever 7. The pressing plate 10 is used when the tile, after being cut by the rotary blade 9, is pressed to be split on the base plate 1. The pressing plate 10 is positioned in front of the rotary blade 9 relative to the moving direction B (described below) of the operation lever 7.
Ordinarily, the rotary blade 9 is made of a super-hard metal (alloy) such as tungsten carbide, etc., and as seen in FIG. 3 the blade 9 is in a relatively thin disk shape with a bolt hole 9b opened at the center. The blade 9 has cutting edge 9a on the rim portion. The cutting edge 9a is in a V-shaped cross section.
The blade 9 is mounted to the base part 8 of the operating lever 7 via an attachment shaft 11. The attachment shaft 11 is passed through the bolt hole 9b of the rotary blade 9 and is fastened to the base part 8 of the operating lever 7 so that the blade 9 is rotatable about the attachment shaft 11.
The above-described pressing plate 10 is mounted to the operating lever 7 via a bolt, which is at the central portion of the upper surface of the pressing plate 10, so that the pressing plate 10 is swingable relative to the operating lever 7. When the rotary blade 9 is being used to cut the tile, the pressing plate 10 is turned upward and held in a high position above the base plate 1.
In use, a tile is placed on the supporting surfaces 3 of the base plate 1, and the rotary blade 9 is pressed against one end of the surface of the tile by pivoting down the pivotal lever 7 in the direction of arrow A in FIG. 2. Then, the operation lever 7 is moved or slid in the direction of arrow B. As a result, a cut is made in the tile surface. When the rotary blade 9 reaches the other end of the tile, the pressing plate 10 is brought down to its "use position" and is pressed against the tile surface. When the tile surface is thus pressed on both sides of the projecting strip 2, the tile is split into two along the cut line.
When making a cut on the tile surface, it is essential that an accurate cut be made along the intended splitting line of the tile surface in order to obtain a good cutting or splitting.
However, in the conventional rotary blade, the attachment shaft is loosely passed through a central hole of the rotary blade to secure a smooth rotation of the rotary blade on the attachment shaft. As a result, the rotary blade has a certain amount of play when the blade is pressed against the tile surface and rotated on the tile surface. Accordingly, the cut made in the tile surface tends to be wide and shallow with collapsed edges, and when the tile is split with such an uneven cut, the split may deviate from the predicted splitting line.
Furthermore, when the rotary blade is pressed against the tile surface and moved, the rotary blade rotates while being directly in contact with the attachment shaft. As a result, there is a large frictional resistance, and a smooth rotation of the blade is hindered. Also, a large operating force is required, which would affect the working efficiency.